| Table XXXIII | |||
|---|---|---|---|
| NO. OF AUTOPSIES | NO. WITH HEMOLYTIC STREPTOCOCCUS | PER CENT WITH HEMOLYTIC STREPTOCOCCUS | |
| Lobar pneumonia with red hepatization | 16 | 6 | 37.5 |
| Lobar pneumonia with red and gray hepatization | 28 | 6 | 21.4 |
| Lobar pneumonia with gray hepatization | 20 | 1 | 5.0 |
Notwithstanding the longer duration of the disease and consequent prolongation of exposure to infection, lobar pneumonia, which has reached the stage of gray hepatization, has shown the smallest incidence of infection with hemolytic streptococci. In the stage of gray hepatization there is diminished susceptibility to secondary infection with this microorganism.
Characteristic histologic changes have been found in the lungs of those who have died with lobar pneumonia followed by invasion of lungs and blood by hemolytic streptococci (e. g., Autopsies 273, 430), but with no evidence of suppuration found at autopsy. Within the pneumonic lung occur patches of necrosis implicating both exuded cells and alveolar walls; in some places nuclei have disappeared; elsewhere nuclear fragments are abundant. In these patches of necrosis Gram-positive streptococci in short chains occur in immense number. In some instances (e. g., Autopsies 273, 346, 479) interlobular septa are very edematous and often contain a network of fibrin; lymphatics are dilated and contain polynuclear leucocytes in abundance. Streptococci are found within these lymphatics. The histologic changes which have been described represent the earliest stages of abscess formation and interstitial suppuration, lesions almost invariably caused by hemolytic streptococci.
Chart 2.—Showing the relation of (a) date of onset of cases in which autopsy demonstrated lobar pneumonia, indicated by upper continuous line with single hatch, and of (b) date of death of these cases, indicated by lower continuous line with double hatch to (c) the occurrence of influenza, indicated by the broken line, and to (d) the total number of fatal cases of pneumonia, indicated by the broken dotted line. Each case of fatal pneumonia is indicated by one division of the scale as numbered on the left of the chart; cases of influenza are indicated by the numbers on the right of the chart.
Relation of Lobar Pneumonia to Influenza.—Some writers have suggested that lobar pneumonia, heretofore observed during the course of epidemics of influenza, is an independent disease with no relation to influenza, both diseases being referable perhaps to similar meteorologic or other conditions. Chart 2, which shows by weeks from September 1 to October 31 the relation of deaths from lobar pneumonia (indicated by double hatch) to deaths from all forms of pneumonia, disproves this suggestion. The two curves follow parallel courses; that representing lobar pneumonia reaches a maximum approximately one week after the outbreak of influenza had reached its height. Lobar pneumonia, like other forms of pneumonia, was secondary to influenza. When a chart is plotted to represent the dates of onset of fatal cases of lobar pneumonia (indicated by single hatch in Chart 2), it becomes evident that the greatest number of these cases of pneumonia had their onset at the beginning of the influenza epidemic, approximately one week before it reached its height. Fatal lobar pneumonia developed less frequently in the latter part of the epidemic; to obtain an explanation of this relation it is necessary to chart separately cases of lobar pneumonia with secondary streptococcus infection, for we have already learned that streptococcus infection was the predominant cause of death in the early period of the influenza epidemic. Exclusion of these instances of secondary streptococcus infection makes no noteworthy change in the character of the chart. Fatal lobar pneumonia, like all forms of fatal pneumonia (p. [140]), was more frequent in the first half than in the second half of the epidemic. This difference is referable either to greater virulence of the virus of influenza or to the greater susceptibility of those first selected by the disease or, as more probable, to conditions such as crowding together of patients with influenza, favoring the transmission of microorganisms which cause pneumonia.
Bronchopneumonia
For the purpose of the present study it is convenient to group together instances of bronchopneumonia which have been unaccompanied, on the one hand, by lobar pneumonia (p. [155]) or, on the other hand, by suppuration, which with few exceptions is caused by hemolytic streptococci or by staphylococci. A group of cases in which lobar and bronchopneumonia have occurred in the same individual have already been considered. In many instances, bronchopneumonia is accompanied by abscess formation or by some other form of suppuration; these lesions will be discussed elsewhere.
Bronchopneumonia unaccompanied by lobar pneumonia or by suppuration occurred in 80 autopsies.
Pneumonic consolidation distributed with relation to the bronchi exhibits considerable variety, and an attempt to define a type of bronchopneumonia characteristic of influenza would be futile. Nevertheless, the bronchopneumonia of influenza has in many instances distinctive characters.